In the central nervous system, the brain and spinal cord are surrounded by a clear and colorless fluid termed cerebrospinal fluid (CSF). In addition, the CSF fills inside brain chambers called ventricles. Normally, CSF is produced by intra ventricular organelles, the choroids plexus, and flows through the ventricles and exits the brain through several foramina where its bathes the surfaces of the brain and spinal cord and finally absorbed into the bloodstream. The balance between production and absorption of CSF is critically important. Ideally, the fluid is almost completely absorbed into the bloodstream as it circulates; however, there are circumstances which, when present, will prevent or disturb the production or absorption of CSF, or which will inhibit its normal flow. When this balance is disturbed, hydrocephalus will result. Hydrocephalus is characterized by an abnormal dilation of the brain ventricles. This dilation can cause potentially harmful pressure on the tissues of the brain and can cause a wide variety of symptoms such as headache and may lead to death. To overcome the deleterious effect of the excess of CSF a divergence of fluids from the brain ventricle via a ventricular shunt is required.
The etiology for hydrocephalus may be congenital or acquired. Congenital hydrocephalus can result from genetic inheritance (aqueductal stenosis) or developmental disorders such as those associated with neural tube defects including spina bifida and encephalocele. Other acquired causes include, intraventricular hemorrhage (one of the complications of premature birth), infections, tumors, traumatic head injury and intra cranial bleeding. In addition, many people develop hydrocephalus even when none of these factors are present.
Hydrocephalus is most often treated with the surgical placement of a shunt system. A ventricular shunt-tube is placed to drain fluid from the ventricular system in the brain to an external reservoir (ventriculostomy) or to a cavity in the body, for instance a cavity of the abdomen (ventriculo-peritoneal shunt). The tubing may contain a valve to ensure the direction, flow or the pressure of the fluid being diverge.
Prior to a ventricular shunt procedure, diagnostic techniques, such as computed tomography scan (CT scan) or magnetic resonance imaging (MRI), are performed to confirm the diagnosis and for the purpose of planning the neurosurgical procedure. In the surgical procedure a ventricular catheter is inserted with the aim to be placed in the body of the ventricle usually, lateral ventricle. The ventricular catheter insertion point and trajectory rely on surface anatomy landmarks, on the preformed imaging data and the surgeon's sense of spatial orientation. However, such techniques are not accurate and may lead to mat-position of said catheter which may cause complications such as bleeding, damage to fundamental brain structure and the like. Misplacement of said catheter usually entails further diagnostic procedures such as CT and MRI as well as additional surgical manipulation with the purpose of re-adjusting catheter location.
Various imaging technologies and methods have been used for computing a trajectory for catheter insertion. For instance, a neuronavigation system provides a real-time trajectory for accurate insertion or placement of a ventricular shunt catheter. However, in many cases it is not used due to cost considerations or due to the long setup time required relative to the time of the ventricular shunt procedure. In some cases such setup time takes more than 45 minutes, and requires fixation of the patient head.
A drawback of prior art systems is the inability to provide accurate placement in a short time or low cost without a significant amount of setup time relatively to the surgical procedure itself. Therefore, there is the need for an apparatus and methods for fast, cheap and accurate placement of a catheter or shunt into brain ventricles. Such method and apparatus will reduce morbidity and mortality while enhance time needed for the procedure at lower costs.